1. Field of the Invention
This invention relates to an air bag inflation gas generator to feed combustion gas for inflation of air bags such as air bags for absorbing collision shocks, life jackets, rafts, and escape chutes.
2. Description of the Known Art
A shock absorber to protect a passenger car driver from shocks at collision accidents comprises an air bag, for example, having a capacity of 60 liters and a gas generator to inflate the air bag with gas. At a collision accident of a passenger car, explosives or other gas generating agents having a similar composition thereto, which are charged in the gas generator, are ignited and burnt to produce gas. The air bag is instantaneously inflated by the resultant gas for driver protection against any collision shocks, thereby avoiding possible serious injury of the driver.
FIG. 11 shows a prior air bag inflation gas generator disclosed in Japanese Patent Application Laid-open Print No. 155857/1990. In the drawing, the reference numeral 1 shows a combustion chamber containing a plurality of gas generating agents 2 in the stacked state.
The gas generating agents 2 are a circular plate having a through hole 3 at the center, and the through hole 3 accommodates an ignition agent 4.
These gas generating agents 2 are accommodated in a concealed container 5. At the center of this concealed container 5, a concave part 6 is formed to be depressed toward the through hole 3 of the gas generating agents 2.
In the concave part 6 is provided an igniter 7 to burn the gas generating agents 2.
The combustion chamber 1 has a combustion chamber filter 8 disposed along its inner wall. And, a plenum chamber 10 annually surrounds the combustion chamber 1 and receives gas flow through an orifice 9 from the combustion chamber filter 8.
The plenum chamber 10 contains a plenum chamber filter consisting of an upper filter 11 and a gas filter 12.
The plenum chamber 10 contains a gas outlet 13 to supply the gas flow from the gas filter 12 to an air bag (not shown).
In this type of air bag inflation gas generator, the powder in the igniter 7 burns when the igniter 7 is energized. The igniter 7 in turn causes the ignition agent 4 to burn and the gas generating agents 2 are burned. Gas from the gas generating agents 2 flows into the plenum chamber 10 through a combustion chamber filter 5 arranged along the inner wall of the combustion chamber 1. The gas is purified by the upper filter 11 and the gas filter 12 and flows into the air bag through the gas outlet 13. The air bag can be completely inflated within a very short time, for example, approximately 0.04 second.
That air bag inflation gas generator, however, has drawbacks that the combustion gas capacity of the gas generating agents 2 is limited and the purifying performance of the combustion gas is also limited.
Specifically, when the air bag for a front passenger is inflated, because the front passenger seat has a different riding environment from the driver seat and a passenger takes various positions, and when a child takes the front passenger seat, physical features are different from an adult, requiring, for example, an air bag to have a large capacity of about 2.5 times of a conventional air bag for the driver seat. Therefore, it has been demanded that the combustion gas capacity of the gas generating agents is large and the gas generator for air bag inflation can purify the large volume of combustion gas surely.
The present inventor has developed a gas generator for inflating an air bag which has remedied the conventional problems and filed Japanese Patent Application No. 299116/1991 (filing date: Nov. 14, 1991).
This air bag inflation gas generator, as shown in FIG. 12, has a longitudinal outer cylindrical member 14 having a plurality of gas outlets 15 formed at the outer periphery, an inner cylindrical member 16 which is inserted in the outer cylindrical member 14 and has gas flow holes 17 formed at the outer periphery, a final filter 18 disposed between the outer cylindrical member 14 and the inner cylindrical member 16, a plurality of gas generating agents 20 accommodated in the inner cylindrical member 16 in the stacked state in its longitudinal direction and having a through hole 19 formed at the center, and an igniter 21 and an ignition agent 22 disposed at one end of the inner cylindrical member 16. And, a partition member 23 for shielding the through holes 19 of the gas generating agents 20 is disposed between the gas generating agents 20 positioned at the center of the inner cylindrical member 16.
And, the gas generating agents 20 and the ignition agent 22 are accommodated in a gas generating agent pack 24.
With this air bag inflation gas generator, the combustion gas capacity of the gas generating agents 20 can be largely increased over those previously known, and a large volume of combustion gas can be surely purified.
With the partition member 23, the volume of the combustion gas flowing into the air bag at the initial inflation of the air bag can be easily and surely controlled. And, at the initial inflation of the air bag, rapid flow of combustion gas into the air bag can be effectively prevented. Thus, impact against a passenger can be effectively eased.
However, such an air bag inflation gas generator merely accommodates the gas generating agent pack 24 in the inner cylindrical member 16, so that the space between the ignition agent 22 and the igniter 21 in the gas generating agent pack may not be securely retained, and particularly, when the space between the igniter 21 and the ignition agent 22 is widened, the ignition performance may possibly be lowered.
And, in such an air bag inflation gas generator, after disposing an end cap 26 within an opening 25 of the outer cylindrical member 14, a wall face 27 of the opening 25 is caulked using the inner cylindrical member 16 as a support for the end cap 26 to mount the end cap 26 on the opening 25. This procedure may apply an unreasonable load to the inner cylindrical member 16.
Further, since a caulking face 28 of the end cap 26 is flat, wall 27 of the opening 25 has to be bent at an angle of about 90 degrees. This may result in causing cracks in the opening 25.